Current Parkinson's treatments can help manage symptoms to some extent but may become less effective as the disease progresses.

Drugs 'Not Futile'

Every day for a year, participants took either creatine, minocycline, or a drug containing no medicine (placebo). They didn't know which treatment they had been given.

Both creatine and minocycline were "not futile" in slowing Parkinson's progression, the researchers write. "Not futile" means that the compounds didn't appear to be worthless, but it doesn't prove it met standards for effectiveness.

Creatine and minocycline might be candidates for further research, write Ravina and colleagues. However, they note that considerations such as safety, tolerability, activity, cost, and availability must first be weighed.

Side Effects

Both compounds were generally well tolerated, but minocycline was "less well tolerated" than creatine, the researchers write.

The three most commonly reported adverse events across all three groups were upper respiratory symptoms, joint pain, and nausea.

The minocycline group had seven cases of tooth discoloration and four cases of skin discoloration. One person in the minocycline group quit the study due to tooth discoloration, the researchers note.